The invention relates to a process of hydrocyanation of unsaturated organic compounds.
The French Pat. No. 2,069,411 discloses a process for an addition of hydrogen cyanide to olefins in the presence of a complex of zerovalent nickel. The catalysts may be represented by the formula (M'R'.sub.3).sub.3 Ni wherein M' represents phosphorus and R' represents a substituted or unsubstituted aryl. The catalysts can be prepared in advance or may be formed in situ. In the latter case a divalent nickel compound having a ligand M'R'.sub.3 and a reducing agent is used. The hydrocyanation reaction may be performed within or without a solvent. The solvent which is liquid at the reaction temperature and inert towards the components of the reaction mixture, is always an organic compound usually a hydrocarbon like benzene or styrene or a nitrile, like acetonitrile or benzonitrile, wherein the reacting olefin is completely dissolved. Very often the ligand may serve as a solvent. The reaction is performed without adding any water to the components of the reacting system.
One of the major inconveniences of this type of process resides in the difficulties which are encountered after the reaction in separating the hydrocyanated products from the catalytic solution, which usually includes several constituents (a nickel complex in excess of a phosphorus containing ligand and a cocatalyst, usually a Lewis acid) especially as far as reutilization of the latter is considered. This separation is difficult and incomplete. Especially a substantial loss in catalyst is noted as well as the presence of catalyst in the separated hydrocyanated products.
In an article by F. Joo and M. T. Beck (Reaction Kinetics and Catalysis Letters, Vol. 2, No. 3, 257-263 (1975) these authors described their work concerning the use of a catalytic solution, which is obtained by mixing an aqueous acid solution of an Ru(III) compound and diphenyl phosphino-benzene-m-sulfonic acid, for the hydrogenation of cetocarboxylic acids.